ABSTRACT: Environmental Health Data Science Center (EHDSC) In support of our renewal application for the NIEHS-funded HERCULES: Exposome Research Center, we propose an Environmental Health Data Science Center (EHDSC). The Big Data to Knowledge (BD2K) community refers to a ?data ecosystem? consisting of interconnected, mutually-dependent systems and elements. This ecosystem concept provides a helpful metaphor in the ?big data? setting where investigators often encounter data with high volume (many measurements), high velocity (rapid throughput), and high variety (very different types) and varying levels of `veracity' (accuracy) over time. All of these concepts are clearly in play within exposome research, both in general and within HERCULES projects in particular. The EHDSC consolidates the interdisciplinary expertise necessary to provide such support to HERCULES and facilitates the application of the exposome concept within environmental health in a more comprehensive fashion than could be accomplished by independent, individual project teams via three specific aims: Specific Aim 1. Expand and foster a data ecosystem for exposome related research. The diverse and heterogeneous nature of data relating to the concept of the exposome demands flexible and adaptable support systems for data collection, integration, management, query, linkage, and analysis, while maintaining rigor and reproducibility. This aim adds an exposome perspective to NIH's broader BD2K effort, a perspective clearly relating to NIEHS goals but not a primary focus in current BD2K efforts. Specific Aim 2. Expand and foster an analytic ecosystem for exposome related research. The data systems from Aim 1 mandate novel elements of both data analytics (rapid but broad scale summaries of trends and associations) and analysis (hypothesis-driven calculations assessing links between exposome data and detailed epidemiologic and systems biologic outcomes, models, and processes). The complex nature of the data requires the EHDSC to provide dedicated, diverse, interdisciplinary expertise to develop accurate and reliable computational and statistical tools for exposome analysis pipelines, particularly when dealing with asynchronous high volume and high velocity data streams of potentially varying accuracy. Specific Aim 3. Expand and foster a collaborative ecosystem for exposome related research. The dedicated efforts in Aims 1 and 2 provide the workbench to support HERCULES pilot programs, assist with research proposal development, career development, and communication of scientific results to HERCULES community partners. Due to the rapid evolution of available data and tools for analysis, related training efforts for students, faculty, research staff, collaborators, and community members will be an essential component of the EHDSC allowing expert assistance in each step of the exposome research pipeline.